1. Field of the Invention
The present invention relates to a disc-selectable player for driving a predetermined disc selected from a plurality of discs, and more particularly to a disc-selectable player in which a disc can assuredly be selected, but having a simple structure, and which comprises a disc drive portion for driving a selected disc that cannot be loosened by external force.
2. Related Art Description
A disc changer of a type mounted on a vehicle has been put to practical use as a disc-selectable player for playing a predetermined disc selected from a plurality of discs.
After a magazine accommodating a plurality of discs has been loaded into the conventional disc changer to be mounted on a vehicle, a predetermined disc is ejected from the magazine so that the playing operation is performed. The structure for ejecting the disc from the magazine and for playing it is so arranged that a moveable chassis, on which a disc ejection mechanism is mounted, is moved to a selection position at which any one of a plurality of the discs is selected. At this position, the disc is introduced into the moveable chassis, and then the disc is conveyed to a disc drive portion by the moveable chassis, the disc is clamped by a turn table at the conveyed position so that the disc is rotated, and a pickup performs the disc playing operation.
However, the structure of the foregoing disc changer so arranged that the disc is conveyed to the disc drive portion by the moveable chassis to be played, and the disc, which has been played, is returned to a vacant space in the magazine by the moveable chassis, takes a too long a time from the instant the disc is ejected to the instant the played is commenced. Further, it also takes too long a time to return the played disc into the magazine to commence the next play. Therefore, if the disc is a CD (Compact Disc), the next play of music is interrupted for an excessively long time.
Accordingly, a disc changer of a type comprising a moveable disc drive portion shown in FIG. 13 has been considered. The disc changer of this type comprises a moveable portion 1 on which all of elements of the disc drive portion, such as a turn table 2, a motor 3 for driving the turn table 2, a disc clamper 4 and a pickup 5, are mounted. When the overall body of the moveable portion 1 is moved upwards/downwards to the position at which the disc in the magazine M is selected, a disc D is, at the foregoing position, ejected from the magazine M. Further, the playing operation is performed in the moveable portion 1 positioned at the foregoing position.
The foregoing system reduces the time taken to eject and change the disc.
However, the disc changer structured as shown in FIG. 13 has the following problems.
(a) When the upward/downward operation of the moveable portion 1 is stopped, the height which the moveable portion 1 reaches tends to deviate from its nominal position. Therefore, the position at which the moveable portion 1 faces the disc D to be selected can deviate if the intervals between the stacked discs D in the magazine are too short. As a result, the disc cannot assuredly be ejected. It might be considered feasible to employ a reproduction structure in which the disc D is clamped in the moveable portion 1 in a state where the disc D is pulled out intermediately from the magazine M. If the position at which the moveable portion 1 stops deviates in this case, a portion of the disc D clamped in the moveable portion 1 comes in contact with a partition plate or a tray in the magazine M. As a result, the disc D cannot assuredly be rotated.
(b) A force transmission mechanism for transmitting the force of the motor to move the moveable portion 1 upwards/downwards always involves looseness such as a backlash. Therefore, if the foregoing disc changer is mounted on vehicle, the moveable portion 1, which is performing the playing operation, is loosened due to vibrations of the car body and the like. As a result, the disc tracking servo and focusing servo are affected adversely. What is worse, the disc track which is being played can easily be jumped.
(c) Since the foregoing disc changer must have a disc ejection mechanism for ejecting a predetermined disc D from the magazine M and a clamping mechanism comprising a cam for moving the clamper 4 to clamp the disc D to the turn table 2, the internal structure of the moveable portion 1 becomes too complicated. In particular, the needed space for the motor serving as a drive source for driving the disc ejection mechanism and mounted on the moveable portion 1 causes the overall size of the moveable portion 1 to be excessively large.
(d) During a period in which a predetermined disc D ejected from the magazine M into the moveable portion 1 is being played, another disc D left in the magazine M is sometimes undesirably ejected toward the moveable portion 1 due to external vibrations such as vibrations of the car body. In order to prevent this, a restriction member for preventing the undesirable ejection of the left disc D must be disposed in front of the magazine M. However, the restriction member must be removed from the movement passage for the disc D not to block the movement passage when a desired disc D is selected and ejected. Further, the restriction member must be moved to the position to block the position in front of the magazine M. Therefore, a mechanism for operating the restriction member must also be provided, complicating the apparatus.